using System;
using System.Data;
using System.Xml;
using System.Data.OleDb;
using System.Collections;

namespace Geekees.Common.Controls.Demo
{
	/// <summary>
	/// The OleDbHelper class is intended to encapsulate high performance, scalable best practices for 
	/// common uses of OleDbClient.
	/// </summary>
	public sealed class OleDbHelper
	{
		#region private utility methods & constructors

		//Since this class provides only static methods, make the default constructor private to prevent 
		//instances from being created with "new OleDbHelper()".
		private OleDbHelper() { }

		/// <summary>
		/// This method is used to attach array's of OleDbParameters to an OleDbCommand.
		/// 
		/// This method will assign a value of DbNull to any parameter with a direction of
		/// InputOutput and a value of null.  
		/// 
		/// This behavior will prevent default values from being used, but
		/// this will be the less common case than an intended pure output parameter (derived as InputOutput)
		/// where the user provided no input value.
		/// </summary>
		/// <param name="command">The command to which the parameters will be added</param>
		/// <param name="commandParameters">an array of OleDbParameters tho be added to command</param>
		private static void AttachParameters( OleDbCommand command, OleDbParameter[] commandParameters )
		{
			foreach( OleDbParameter p in commandParameters )
			{
				//check for derived output value with no value assigned
				if( ( p.Direction == ParameterDirection.InputOutput ) && ( p.Value == null ) )
				{
					p.Value = DBNull.Value;
				}

				command.Parameters.Add( p );
			}
		}

		/// <summary>
		/// This method assigns an array of values to an array of OleDbParameters.
		/// </summary>
		/// <param name="commandParameters">array of OleDbParameters to be assigned values</param>
		/// <param name="parameterValues">array of objects holding the values to be assigned</param>
		private static void AssignParameterValues( OleDbParameter[] commandParameters, object[] parameterValues )
		{
			if( ( commandParameters == null ) || ( parameterValues == null ) )
			{
				//do nothing if we get no data
				return;
			}

			// we must have the same number of values as we pave parameters to put them in
			if( commandParameters.Length != parameterValues.Length )
			{
				throw new ArgumentException( "Parameter count does not match Parameter Value count." );
			}

			//iterate through the OleDbParameters, assigning the values from the corresponding position in the 
			//value array
			for( int i = 0, j = commandParameters.Length; i < j; i++ )
			{
				commandParameters[i].Value = parameterValues[i];
			}
		}

		/// <summary>
		/// This method opens (if necessary) and assigns a connection, transaction, command type and parameters 
		/// to the provided command.
		/// </summary>
		/// <param name="command">the OleDbCommand to be prepared</param>
		/// <param name="connection">a valid OleDbConnection, on which to execute this command</param>
		/// <param name="transaction">a valid OleDbTransaction, or 'null'</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param> 
		/// <param name="commandParameters">an array of OleDbParameters to be associated with the command or 'null' if no parameters are required</param>
		private static void PrepareCommand( OleDbCommand command, OleDbConnection connection, OleDbTransaction transaction, CommandType commandType, string commandText, OleDbParameter[] commandParameters )
		{
			//if the provided connection is not open, we will open it
			if( connection.State != ConnectionState.Open )
			{
				connection.Open();
			}

			//associate the connection with the command
			command.Connection = connection;

			//set the command text (stored procedure name or OleDb statement)
			command.CommandText = commandText;

			//if we were provided a transaction, assign it.
			if( transaction != null )
			{
				command.Transaction = transaction;
			}

			//set the command type
			command.CommandType = commandType;

			//attach the command parameters if they are provided
			if( commandParameters != null )
			{
				AttachParameters( command, commandParameters );
			}

			return;
		}


		#endregion private utility methods & constructors

		#region ExecuteNonQuery

		/// <summary>
		/// Execute an OleDbCommand (that returns no resultset and takes no parameters) against the database specified in 
		/// the connection string. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders");
		/// </remarks>
		/// <param name="connectionString">a valid connection string for an OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery( string connectionString, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteNonQuery( connectionString, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns no resultset) against the database specified in the connection string 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <param name="commandParameters">an array of OleDbParameters used to execute the command</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery( string connectionString, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create & open an OleDbConnection, and dispose of it after we are done.
			using( OleDbConnection cn = new OleDbConnection( connectionString ) )
			{
				cn.Open();

				//call the overload that takes a connection in place of the connection string
				return ExecuteNonQuery( cn, commandType, commandText, commandParameters );
			}
		}

		/// <summary>
		/// Execute a stored procedure via an OleDbCommand (that returns no resultset) against the database specified in 
		/// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  int result = ExecuteNonQuery(connString, "PublishOrders", 24, 36);
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a OleDbConnection</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery( string connectionString, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( connectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteNonQuery( connectionString, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteNonQuery( connectionString, CommandType.StoredProcedure, spName );
			}
		}

		/// <summary>
		/// Execute an OleDbDbCommand (that returns no resultset and takes no parameters) against the provided OleDbConnection. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders");
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery( OleDbConnection connection, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteNonQuery( connection, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns no resultset) against the specified OleDbConnection 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery( OleDbConnection connection, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create a command and prepare it for execution
			OleDbCommand cmd = new OleDbCommand();
			PrepareCommand( cmd, connection, (OleDbTransaction)null, commandType, commandText, commandParameters );

			//finally, execute the command.
			return cmd.ExecuteNonQuery();
		}

		/// <summary>
		/// Execute a stored procedure via an OleDbCommand (that returns no resultset) against the specified OleDbConnection 
		/// using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  int result = ExecuteNonQuery(conn, "PublishOrders", 24, 36);
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery( OleDbConnection connection, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( connection.ConnectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteNonQuery( connection, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteNonQuery( connection, CommandType.StoredProcedure, spName );
			}
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns no resultset and takes no parameters) against the provided OleDbTransaction. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(trans, CommandType.StoredProcedure, "PublishOrders");
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery( OleDbTransaction transaction, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteNonQuery( transaction, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns no resultset) against the specified OleDbTransaction
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(trans, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery( OleDbTransaction transaction, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create a command and prepare it for execution
			OleDbCommand cmd = new OleDbCommand();
			PrepareCommand( cmd, transaction.Connection, transaction, commandType, commandText, commandParameters );

			//finally, execute the command.
			return cmd.ExecuteNonQuery();
		}

		/// <summary>
		/// Execute a stored procedure via an OleDbCommand (that returns no resultset) against the specified 
		/// OleDbTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  int result = ExecuteNonQuery(conn, trans, "PublishOrders", 24, 36);
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="spName">the name of the stored procedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery( OleDbTransaction transaction, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( transaction.Connection.ConnectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteNonQuery( transaction, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteNonQuery( transaction, CommandType.StoredProcedure, spName );
			}
		}

		#endregion ExecuteNonQuery

		#region ExecuteDataSet

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the database specified in 
		/// the connection string. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(connString, CommandType.StoredProcedure, "GetOrders");
		/// </remarks>
		/// <param name="connectionString">a valid connection string for an OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset( string connectionString, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteDataset( connectionString, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset) against the database specified in the connection string 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(connString, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connectionString">a valid connection string for an OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param> 
		/// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset( string connectionString, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create & open an OleDbConnection, and dispose of it after we are done.
			using( OleDbConnection cn = new OleDbConnection( connectionString ) )
			{
				cn.Open();

				//call the overload that takes a connection in place of the connection string
				return ExecuteDataset( cn, commandType, commandText, commandParameters );
			}
		}

		/// <summary>
		/// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the database specified in 
		/// the conneciton string using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(connString, "GetOrders", 24, 36);
		/// </remarks>
		/// <param name="connectionString">a valid connection string for an OleDbConnection</param>
		/// <param name="spName">the name of the stored procedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset( string connectionString, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( connectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteDataset( connectionString, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteDataset( connectionString, CommandType.StoredProcedure, spName );
			}
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the provided OleDbConnection. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(conn, CommandType.StoredProcedure, "GetOrders");
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset( OleDbConnection connection, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteDataset( connection, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset) against the specified OleDbConnection 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(conn, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param> 
		/// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset( OleDbConnection connection, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create a command and prepare it for execution
			OleDbCommand cmd = new OleDbCommand();
			PrepareCommand( cmd, connection, (OleDbTransaction)null, commandType, commandText, commandParameters );

			//create the DataAdapter & DataSet
			OleDbDataAdapter da = new OleDbDataAdapter( cmd );
			DataSet ds = new DataSet();

			//fill the DataSet using default values for DataTable names, etc.
			da.Fill( ds );

			//return the dataset
			return ds;
		}

		/// <summary>
		/// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the specified OleDbConnection 
		/// using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(conn, "GetOrders", 24, 36);
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset( OleDbConnection connection, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( connection.ConnectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteDataset( connection, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteDataset( connection, CommandType.StoredProcedure, spName );
			}
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the provided OleDbTransaction. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(trans, CommandType.StoredProcedure, "GetOrders");
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param> 
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset( OleDbTransaction transaction, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteDataset( transaction, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset) against the specified OleDbTransaction
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(trans, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param> 
		/// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset( OleDbTransaction transaction, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create a command and prepare it for execution
			OleDbCommand cmd = new OleDbCommand();
			PrepareCommand( cmd, transaction.Connection, transaction, commandType, commandText, commandParameters );

			//create the DataAdapter & DataSet
			OleDbDataAdapter da = new OleDbDataAdapter( cmd );
			DataSet ds = new DataSet();

			//fill the DataSet using default values for DataTable names, etc.
			da.Fill( ds );

			//return the dataset
			return ds;
		}

		/// <summary>
		/// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the specified 
		/// OleDbTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  DataSet ds = ExecuteDataset(trans, "GetOrders", 24, 36);
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>a dataset containing the resultset generated by the command</returns>
		public static DataSet ExecuteDataset( OleDbTransaction transaction, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( transaction.Connection.ConnectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteDataset( transaction, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteDataset( transaction, CommandType.StoredProcedure, spName );
			}
		}

		#endregion ExecuteDataSet

		#region ExecuteReader

		/// <summary>
		/// this enum is used to indicate weather the connection was provided by the caller, or created by OleDbHelper, so that
		/// we can set the appropriate CommandBehavior when calling ExecuteReader()
		/// </summary>
		private enum OleDbConnectionOwnership
		{
			/// <summary>Connection is owned and managed by OleDbHelper</summary>
			Internal,
			/// <summary>Connection is owned and managed by the caller</summary>
			External
		}

		/// <summary>
		/// Create and prepare an OleDbCommand, and call ExecuteReader with the appropriate CommandBehavior.
		/// </summary>
		/// <remarks>
		/// If we created and opened the connection, we want the connection to be closed when the DataReader is closed.
		/// 
		/// If the caller provided the connection, we want to leave it to them to manage.
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection, on which to execute this command</param>
		/// <param name="transaction">a valid OleDbTransaction, or 'null'</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param> 
		/// <param name="commandParameters">an array of OleDbParameters to be associated with the command or 'null' if no parameters are required</param>
		/// <param name="connectionOwnership">indicates whether the connection parameter was provided by the caller, or created by OleDbHelper</param>
		/// <returns>OleDbDataReader containing the results of the command</returns>
		private static OleDbDataReader ExecuteReader( OleDbConnection connection, OleDbTransaction transaction, CommandType commandType, string commandText, OleDbParameter[] commandParameters, OleDbConnectionOwnership connectionOwnership )
		{
			//create a command and prepare it for execution
			OleDbCommand cmd = new OleDbCommand();
			PrepareCommand( cmd, connection, transaction, commandType, commandText, commandParameters );

			//create a reader
			OleDbDataReader dr;

			// call ExecuteReader with the appropriate CommandBehavior
			if( connectionOwnership == OleDbConnectionOwnership.External )
			{
				dr = cmd.ExecuteReader();
			}
			else
			{
				dr = cmd.ExecuteReader( CommandBehavior.CloseConnection );
			}

			return dr;
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the database specified in 
		/// the connection string. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  OleDbDataReader dr = ExecuteReader(connString, CommandType.StoredProcedure, "GetOrders");
		/// </remarks>
		/// <param name="connectionString">a valid connection string for an OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
		public static OleDbDataReader ExecuteReader( string connectionString, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteReader( connectionString, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset) against the database specified in the connection string 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  OleDbDataReader dr = ExecuteReader(connString, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connectionString">a valid connection string for an OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <param name="commandParameters">an array of OleDbParameters used to execute the command</param>
		/// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
		public static OleDbDataReader ExecuteReader( string connectionString, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create & open an OleDbbConnection
			OleDbConnection cn = new OleDbConnection( connectionString );
			cn.Open();

			try
			{
				//call the private overload that takes an internally owned connection in place of the connection string
				return ExecuteReader( cn, null, commandType, commandText, commandParameters, OleDbConnectionOwnership.Internal );
			}
			catch
			{
				//if we fail to return the OleDbDataReader, we neeed to close the connection ourselves
				cn.Close();
				throw;
			}
		}

		/// <summary>
		/// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the database specified in 
		/// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  OleDbDataReader dr = ExecuteReader(connString, "GetOrders", 24, 36);
		/// </remarks>
		/// <param name="connectionString">a valid connection string for an OleDbConnection</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
		public static OleDbDataReader ExecuteReader( string connectionString, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( connectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteReader( connectionString, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteReader( connectionString, CommandType.StoredProcedure, spName );
			}
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the provided OleDbConnection. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  OleDbDataReader dr = ExecuteReader(conn, CommandType.StoredProcedure, "GetOrders");
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>
		/// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
		public static OleDbDataReader ExecuteReader( OleDbConnection connection, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteReader( connection, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset) against the specified OleDbConnection 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  OleDbDataReader dr = ExecuteReader(conn, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
		/// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
		public static OleDbDataReader ExecuteReader( OleDbConnection connection, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//pass through the call to the private overload using a null transaction value and an externally owned connection
			return ExecuteReader( connection, (OleDbTransaction)null, commandType, commandText, commandParameters, OleDbConnectionOwnership.External );
		}

		/// <summary>
		/// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the specified OleDbConnection 
		/// using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  OleDbDataReader dr = ExecuteReader(conn, "GetOrders", 24, 36);
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="spName">the name of the stored procedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
		public static OleDbDataReader ExecuteReader( OleDbConnection connection, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( connection.ConnectionString, spName );

				AssignParameterValues( commandParameters, parameterValues );

				return ExecuteReader( connection, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteReader( connection, CommandType.StoredProcedure, spName );
			}
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset and takes no parameters) against the provided OleDbTransaction. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  OleDbDataReader dr = ExecuteReader(trans, CommandType.StoredProcedure, "GetOrders");
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param>  
		/// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
		public static OleDbDataReader ExecuteReader( OleDbTransaction transaction, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteReader( transaction, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute an OleDbCommand (that returns a resultset) against the specified OleDbTransaction
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///   OleDbDataReader dr = ExecuteReader(trans, CommandType.StoredProcedure, "GetOrders", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or PL/SQL command</param> 
		/// <param name="commandParameters">an array of OleDbParameters used to execute the command</param>
		/// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
		public static OleDbDataReader ExecuteReader( OleDbTransaction transaction, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//pass through to private overload, indicating that the connection is owned by the caller
			return ExecuteReader( transaction.Connection, transaction, commandType, commandText, commandParameters, OleDbConnectionOwnership.External );
		}

		/// <summary>
		/// Execute a stored procedure via an OleDbCommand (that returns a resultset) against the specified
		/// OleDbTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  OleDbDataReader dr = ExecuteReader(trans, "GetOrders", 24, 36);
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an OleDbDataReader containing the resultset generated by the command</returns>
		public static OleDbDataReader ExecuteReader( OleDbTransaction transaction, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( transaction.Connection.ConnectionString, spName );

				AssignParameterValues( commandParameters, parameterValues );

				return ExecuteReader( transaction, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteReader( transaction, CommandType.StoredProcedure, spName );
			}
		}

		#endregion ExecuteReader

		#region ExecuteScalar

		/// <summary>
		/// Execute a OleDbCommand (that returns a 1x1 resultset and takes no parameters) against the database specified in 
		/// the connection string. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int orderCount = (int)ExecuteScalar(connString, CommandType.StoredProcedure, "GetOrderCount");
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-OleDb command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar( string connectionString, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteScalar( connectionString, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute a OleDbCommand (that returns a 1x1 resultset) against the database specified in the connection string 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int orderCount = (int)ExecuteScalar(connString, CommandType.StoredProcedure, "GetOrderCount", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-OleDb command</param>
		/// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar( string connectionString, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create & open a OleDbConnection, and dispose of it after we are done.
			using( OleDbConnection cn = new OleDbConnection( connectionString ) )
			{
				cn.Open();

				//call the overload that takes a connection in place of the connection string
				return ExecuteScalar( cn, commandType, commandText, commandParameters );
			}
		}

		/// <summary>
		/// Execute a stored procedure via a OleDbCommand (that returns a 1x1 resultset) against the database specified in 
		/// the conneciton string using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  int orderCount = (int)ExecuteScalar(connString, "GetOrderCount", 24, 36);
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a OleDbConnection</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar( string connectionString, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( connectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteScalar( connectionString, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteScalar( connectionString, CommandType.StoredProcedure, spName );
			}
		}

		/// <summary>
		/// Execute a OleDbCommand (that returns a 1x1 resultset and takes no parameters) against the provided OleDbConnection. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int orderCount = (int)ExecuteScalar(conn, CommandType.StoredProcedure, "GetOrderCount");
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-OleDb command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar( OleDbConnection connection, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteScalar( connection, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute a OleDbCommand (that returns a 1x1 resultset) against the specified OleDbConnection 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int orderCount = (int)ExecuteScalar(conn, CommandType.StoredProcedure, "GetOrderCount", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-OleDb command</param>
		/// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar( OleDbConnection connection, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create a command and prepare it for execution
			OleDbCommand cmd = new OleDbCommand();
			PrepareCommand( cmd, connection, (OleDbTransaction)null, commandType, commandText, commandParameters );

			//execute the command & return the results
			return cmd.ExecuteScalar();
		}

		/// <summary>
		/// Execute a stored procedure via a OleDbCommand (that returns a 1x1 resultset) against the specified OleDbConnection 
		/// using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  int orderCount = (int)ExecuteScalar(conn, "GetOrderCount", 24, 36);
		/// </remarks>
		/// <param name="connection">a valid OleDbConnection</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar( OleDbConnection connection, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( connection.ConnectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteScalar( connection, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteScalar( connection, CommandType.StoredProcedure, spName );
			}
		}

		/// <summary>
		/// Execute a OleDbCommand (that returns a 1x1 resultset and takes no parameters) against the provided OleDbTransaction. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int orderCount = (int)ExecuteScalar(trans, CommandType.StoredProcedure, "GetOrderCount");
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-OleDb command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar( OleDbTransaction transaction, CommandType commandType, string commandText )
		{
			//pass through the call providing null for the set of OleDbParameters
			return ExecuteScalar( transaction, commandType, commandText, (OleDbParameter[])null );
		}

		/// <summary>
		/// Execute a OleDbCommand (that returns a 1x1 resultset) against the specified OleDbTransaction
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int orderCount = (int)ExecuteScalar(trans, CommandType.StoredProcedure, "GetOrderCount", new OleDbParameter("@prodid", 24));
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-OleDb command</param>
		/// <param name="commandParameters">an array of OleDbParamters used to execute the command</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar( OleDbTransaction transaction, CommandType commandType, string commandText, params OleDbParameter[] commandParameters )
		{
			//create a command and prepare it for execution
			OleDbCommand cmd = new OleDbCommand();
			PrepareCommand( cmd, transaction.Connection, transaction, commandType, commandText, commandParameters );

			//execute the command & return the results
			return cmd.ExecuteScalar();

		}

		/// <summary>
		/// Execute a stored procedure via a OleDbCommand (that returns a 1x1 resultset) against the specified
		/// OleDbTransaction using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  int orderCount = (int)ExecuteScalar(trans, "GetOrderCount", 24, 36);
		/// </remarks>
		/// <param name="transaction">a valid OleDbTransaction</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an object containing the value in the 1x1 resultset generated by the command</returns>
		public static object ExecuteScalar( OleDbTransaction transaction, string spName, params object[] parameterValues )
		{
			//if we got parameter values, we need to figure out where they go
			if( ( parameterValues != null ) && ( parameterValues.Length > 0 ) )
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populet the cache)
				OleDbParameter[] commandParameters = OleDbHelperParameterCache.GetSpParameterSet( transaction.Connection.ConnectionString, spName );

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues( commandParameters, parameterValues );

				//call the overload that takes an array of OleDbParameters
				return ExecuteScalar( transaction, CommandType.StoredProcedure, spName, commandParameters );
			}
			//otherwise we can just call the SP without params
			else
			{
				return ExecuteScalar( transaction, CommandType.StoredProcedure, spName );
			}
		}

		#endregion ExecuteScalar
	}

	/// <summary>
	/// OleDbHelperParameterCache provides functions to leverage a static cache of procedure parameters, and the
	/// ability to discover parameters for stored procedures at run-time.
	/// </summary>
	public sealed class OleDbHelperParameterCache
	{
		#region private methods, variables, and constructors

		//Since this class provides only static methods, make the default constructor private to prevent 
		//instances from being created with "new OleDbHelperParameterCache()".
		private OleDbHelperParameterCache() { }

		private static Hashtable paramCache = Hashtable.Synchronized( new Hashtable() );

		/// <summary>
		/// resolve at run-time the appropriate set of OleDbParameters for a stored procedure
		/// </summary>
		/// <param name="connectionString">a valid connection string for a OleDbConnection</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="includeReturnValueParameter">weather or not to onclude ther return value parameter</param>
		/// <returns></returns>
		private static OleDbParameter[] DiscoverSpParameterSet( string connectionString, string spName, bool includeReturnValueParameter )
		{
			using( OleDbConnection cn = new OleDbConnection( connectionString ) )
			using( OleDbCommand cmd = new OleDbCommand( spName, cn ) )
			{
				cn.Open();
				cmd.CommandType = CommandType.StoredProcedure;

				OleDbCommandBuilder.DeriveParameters( cmd );

				if( !includeReturnValueParameter )
				{
					if( ParameterDirection.ReturnValue == cmd.Parameters[0].Direction )
						cmd.Parameters.RemoveAt( 0 );
				}

				OleDbParameter[] discoveredParameters = new OleDbParameter[cmd.Parameters.Count];

				cmd.Parameters.CopyTo( discoveredParameters, 0 );

				return discoveredParameters;
			}
		}

		//deep copy of cached OleDbParameter array
		private static OleDbParameter[] CloneParameters( OleDbParameter[] originalParameters )
		{
			OleDbParameter[] clonedParameters = new OleDbParameter[originalParameters.Length];

			for( int i = 0, j = originalParameters.Length; i < j; i++ )
			{
				clonedParameters[i] = (OleDbParameter)( (ICloneable)originalParameters[i] ).Clone();
			}

			return clonedParameters;
		}

		#endregion private methods, variables, and constructors

		#region caching functions

		/// <summary>
		/// add parameter array to the cache
		/// </summary>
		/// <param name="connectionString">a valid connection string for an OleDbConnection</param>
		/// <param name="commandText">the stored procedure name or T-OleDb command</param>
		/// <param name="commandParameters">an array of OleDbParamters to be cached</param>
		public static void CacheParameterSet( string connectionString, string commandText, params OleDbParameter[] commandParameters )
		{
			string hashKey = connectionString + ":" + commandText;

			paramCache[hashKey] = commandParameters;
		}

		/// <summary>
		/// retrieve a parameter array from the cache
		/// </summary>
		/// <param name="connectionString">a valid connection string for a OleDbConnection</param>
		/// <param name="commandText">the stored procedure name or T-OleDb command</param>
		/// <returns>an array of OleDbParameters</returns>
		public static OleDbParameter[] GetCachedParameterSet( string connectionString, string commandText )
		{
			string hashKey = connectionString + ":" + commandText;

			OleDbParameter[] cachedParameters = (OleDbParameter[])paramCache[hashKey];

			if( cachedParameters == null )
			{
				return null;
			}
			else
			{
				return CloneParameters( cachedParameters );
			}
		}

		#endregion caching functions

		#region Parameter Discovery Functions

		/// <summary>
		/// Retrieves the set of OleDbParameters appropriate for the stored procedure
		/// </summary>
		/// <remarks>
		/// This method will query the database for this information, and then store it in a cache for future requests.
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a OleDbConnection</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <returns>an array of OleDbParameters</returns>
		public static OleDbParameter[] GetSpParameterSet( string connectionString, string spName )
		{
			return GetSpParameterSet( connectionString, spName, true );
		}

		/// <summary>
		/// Retrieves the set of OleDbParameters appropriate for the stored procedure
		/// </summary>
		/// <remarks>
		/// This method will query the database for this information, and then store it in a cache for future requests.
		/// </remarks>
		/// <param name="connectionString">a valid connection string for an OleDbConnection</param>
		/// <param name="spName">the name of the stored procedure</param>
		/// <param name="includeReturnValueParameter">a bool value indicating weather the return value parameter should be included in the results</param>
		/// <returns>an array of OleDbParameters</returns>
		public static OleDbParameter[] GetSpParameterSet( string connectionString, string spName, bool includeReturnValueParameter )
		{
			string hashKey = connectionString + ":" + spName + ( includeReturnValueParameter ? ":include ReturnValue Parameter" : "" );

			OleDbParameter[] cachedParameters;

			cachedParameters = (OleDbParameter[])paramCache[hashKey];

			if( cachedParameters == null )
			{
				cachedParameters = (OleDbParameter[])( paramCache[hashKey] = DiscoverSpParameterSet( connectionString, spName, includeReturnValueParameter ) );
			}

			return CloneParameters( cachedParameters );
		}

		#endregion Parameter Discovery Functions

	}
}
